LAMP1 and Pseudoxanthoma elasticum: As we could not detect significant differences in LAMP1 between PXE fibroblasts and NHDF neither in medium with 10% FCS nor in medium with 10% LPDS, the increased SA-β-Gal activity in PXE fibroblasts is, therefore, probably not associated with an accumulation of lysosomes, but with increased lysosomal activity or an increased β-galactosidase protein concentration within the lysosomes.